如何解决检查元素是否显示时出现的Stale Element Reference异常？

我希望点击删除按钮后，检查该按钮是否仍显示（测试失败）或已消失（测试通过），但尝试两种方法都触发了报错。

原点击按钮代码 #

# 查找并点击删除按钮
deleteButton = driver.find_element('xpath','//button[@class="added-manually btn btn-info"][contains(text(),"Delete")]')
deleteButton.click()
time.sleep(5)

尝试的方法及报错 #

方法1：调用is_displayed() #

if deleteButton.is_displayed():
    print("Oh no ! Delete button is always present x_x")
else:
    print("Good ! Delete button is not present anymore")

报错信息：

Traceback (most recent call last):
  File "c:\Projets Python\Python Basics\tests\Selenium web\add_remove_elements.py", line 35, in <module>
    if deleteButton.is_displayed():
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\hendb\AppData\Roaming\Python\Python311\site-packages\selenium\webdriver\remote\webelement.py", line 252, in is_displayed
    return self.parent.execute_script(f"/* isDisplayed */return ({isDisplayed_js}).apply(null, arguments);", self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\hendb\AppData\Roaming\Python\Python311\site-packages\selenium\webdriver\remote\webdriver.py", line 405, in execute_script
    return self.execute(command, {"script": script, "args": converted_args})["value"]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\hendb\AppData\Roaming\Python\Python311\site-packages\selenium\webdriver\remote\webdriver.py", line 345, in execute
    self.error_handler.check_response(response)
  File "C:\Users\hendb\AppData\Roaming\Python\Python311\site-packages\selenium\webdriver\remote\errorhandler.py", line 229, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.StaleElementReferenceException: Message: stale element reference: stale element not found
  (Session info: chrome=116.0.5845.96)

方法2：检查元素text长度 #

if len(deleteButton.text)>0:
    print("Yes, the button is not present anymore !")
else:
    print("Ohh, the button is always displayed x_x")

报错信息：

Traceback (most recent call last):
  File "c:\Projets Python\Python Basics\tests\Selenium web\add_remove_elements.py", line 33, in <module>
    print("Yes, the button is not present anymore !")
       ^^^^^^^^^^^^^^^^^
  File "C:\Users\hendb\AppData\Roaming\Python\Python311\site-packages\selenium\webdriver\remote\webelement.py", line 90, in text
    return self._execute(Command.GET_ELEMENT_TEXT)["value"]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\hendb\AppData\Roaming\Python\Python311\site-packages\selenium\webdriver\remote\webelement.py", line 395, in _execute
    return self._parent.execute(command, params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\hendb\AppData\Roaming\Python\Python311\site-packages\selenium\webdriver\remote\webdriver.py", line 345, in execute
    self.error_handler.check_response(response)
  File "C:\Users\hendb\AppData\Roaming\Python\Python311\site-packages\selenium\webdriver\remote\errorhandler.py", line 229, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.StaleElementReferenceException: Message: stale element reference: stale element not found
  (Session info: chrome=116.0.5845.96)

问题原因 #

点击删除按钮后，该元素已从DOM中被移除，你之前保存的deleteButton变量是对原DOM元素的引用，此时已失效，再调用它的任何方法都会触发StaleElementReferenceException。

正确解决方案 #

方案1：重新查找元素并捕获异常 #

点击后重新定位元素，若找不到则说明元素已消失：

import selenium

deleteButton = driver.find_element('xpath','//button[@class="added-manually btn btn-info"][contains(text(),"Delete")]')
deleteButton.click()
time.sleep(5)

# 重新查找元素
try:
    driver.find_element('xpath','//button[@class="added-manually btn btn-info"][contains(text(),"Delete")]')
    print("Oh no ! Delete button is always present x_x")
except selenium.common.exceptions.NoSuchElementException:
    print("Good ! Delete button is not present anymore")

方案2：使用find_elements检查元素数量 #

find_elements会返回匹配的元素列表，若列表为空则元素不存在：

deleteButton = driver.find_element('xpath','//button[@class="added-manually btn btn-info"][contains(text(),"Delete")]')
deleteButton.click()
time.sleep(5)

# 获取所有匹配的元素
delete_buttons = driver.find_elements('xpath','//button[@class="added-manually btn btn-info"][contains(text(),"Delete")]')
if len(delete_buttons) > 0:
    print("Oh no ! Delete button is always present x_x")
else:
    print("Good ! Delete button is not present anymore")

方案3：使用显式等待（推荐，替代time.sleep） #

用Selenium的显式等待等待元素消失，比固定休眠更可靠：

from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.common.exceptions import TimeoutException

deleteButton = driver.find_element('xpath','//button[@class="added-manually btn btn-info"][contains(text(),"Delete")]')
deleteButton.click()

try:
    # 等待10秒，直到元素不可见或不存在
    WebDriverWait(driver, 10).until(
        EC.invisibility_of_element_located(('xpath','//button[@class="added-manually btn btn-info"][contains(text(),"Delete")]'))
    )
    print("Good ! Delete button is not present anymore")
except TimeoutException:
    print("Oh no ! Delete button is always present x_x")

内容的提问来源于stack exchange，提问作者Hend